Shielded enclosures, e.g. rooms which prevent the ingress or egress of RFI or EMI signals have become increasingly more commonplace in the past few years.
This has in part been spurred by the increased awareness of the problems caused by stray or unwanted RFI and EMI signals as well as for security reasons. Typically, such enclosures are used as computer rooms, communication facilities, test chambers or medical rooms.
A shielded entrance, such as a door, is needed in each enclosure to allow for the transfer of personnel and equipment to and from the enclosure. Typically, such doors have been large, heavy, solid metal structures. A shielding means surrounding the door frame has generally consisted of metal finger stock, such as beryllium copper finger stock. Additionally, such doors typically have a raised threshold along the bottom of the door frame so that the finger stock may be used around the entire perimeter of the door.
Experience has shown that such doors require extensive maintenance, in that the metal finger stock tends to set (i.e., become permanently deformed), which reduces its shielding capabilities and necessitates replacement. Additionally, the finger stock often breaks due to metal fatigue and is also subject to corrosion and excessive wear caused by the frequent opening and closing of the door. Further, the force needed to properly close and form a conductive pathway around the entire door is excessively high when using metal finger stock. Likewise, the raised threshold is difficult to traverse, making the movement of equipment a difficult and time-consuming task. The use of inclined ramps or lifts may be needed for the movement of heavy equipment into and out of such enclosures. Lastly, such doors are often left open by its occupants to avoid the problems in repeatedly opening and closing such doors. This practice voids the purpose of the enclosure.
The present invention provides a new and unique shielded door assembly which eliminates the problems associated with finger stock and a raised threshold. The shielded door assembly of the present invention reduces the required closing force as well as eliminates the high threshold while maintaining its shielding integrity.